Audio Systems: Cassette Recorder, pinch roller, rubber roller

Question
As the capstan on the recorder turns and unwinds the tape on the feed reel, the circumference of the tape on the reel will become smaller which would appear to cause the tape passing the head to  become slower. Does the recorder have a constant speed motor and is the decrease in linear tape speed across the head accounted for in the recording as the tape passes the electromagnet in the head OR does the unit have a variable pseed motor and, if so, how is the speed controlled?

Answer
The only reel that has any tension on it is the take up side that pullys the tape back into the cassette.  THe tape speed is held constand by the pinch roller.  If you look at the drive mechanism, you will see a rubber roller that comes up and presses up against a metal post.  That post is what turns and pulls the tape across the tape heads.  That motor controls the tape movement.
Dan